1. Field of the Disclosure
The present disclosure relates to apparatus and methods for diverting fluid in downhole tool applications.
2. Background
Wellbores are drilled in earth's formations using a drill string to produce hydrocarbons (oil and gas) from underground reservoirs. The wells are generally completed by placing a casing (also referred to herein as a “liner” or “drilling tubular”) in the wellbore. The spacing between the liner and the wellbore inside (referred to as the “annulus”) is then filled with cement. The liner is perforated to allow the hydrocarbons to flow from the reservoirs to the surface via production equipment installed inside the liner. Some wells are drilled with drill strings that also include a liner. Such drill strings include an outer string that is made with the liner. The inner string is typically a drill string that includes a drill bit, a bottomhole assembly and a steering device. The inner string is placed inside the outer string and securely attached therein at a suitable location. The pilot bit, bottomhole assembly and steering device extend past the liner to drill a deviated well. To drill a wellbore with such a drill string, a drilling fluid (also referred to as “mud”) is supplied to the inner string. The drilling fluid discharges at the bottom of the pilot bit and returns via the annulus to the surface. During drilling, both the pilot bit and the reamer disintegrate the rock formation into small pieces referred to as the cuttings, which flow with the circulating fluid to the surface via the annulus between the liner and the wellbore wall. In certain case and particularly in highly deviated wells, the cuttings tend to settle at the low side of the wellbore and the flow rate of the circulating fluid is not adequate to cause the cuttings to efficiently flow to the surface. In other cases, it is desired to reduce pressure at the bottom of the wellbore, referred to as equivalent circulation density (“ECD”).
The disclosure herein provides apparatus and methods for drilling wellbore while hole cleaning and for controlling the ECD.